I just had R-40 insulation installed into
the attic. It's still hot up there. I am thing about installing one of those
reflective radiant barriers in the attic. How do I go about installing a
radiant barrier?

There are a couple of ways to do it. You can
lay it directly on top of the existing insulation, but I wouldn't recommend it
if you live in a hot climate. The other method of installing a radiant barrier
in the attic is to staple it to the roof rafters, assuming your roof isn't too
high above the attic floor.

I would recommend buying the radiant barrier in
widths or 3 or 4 feet. Grab a drop light, staple gun, utility knife, the
roll(s) of radiant barrier and a helper and get on up into that attic. Don't
forget to wear protective clothing and a dust mask and try to do this in the
morning before the attic heats up.

If your attic is not platformed you're going to have
to walk the ceiling joists so be careful not to fall through the drywall. You're
going to attach the radiant barrier to the roof rafters. Roll out the radiant
barrier the entire length of the rafters and cut it with your utility knife.
Starting at the bottom, near the eaves, begin stapling it to the face of the
rafters. Make sure the shiny foil surface is facing the open attic - not the
roof. Watch for electrical wiring and don't staple into it. You should be using
1/2" staples.

Continue going across the attic, stapling the
reflective radiant barrier as you go to the rafters. Don't let your helper goof
off. Have him hold the radiant barrier up so you don't get all wrapped up in it.
Once you have the bottom attached you should give your back a break. I know it's
not easy bellying through tight areas of an attic.

Next, attach the opposite end in the same manner,
stapling across the rafters and down each rafter every 8". Once you have that
length of foil barrier installed, roll out another length of it and install it
in the same manner, making sure you overlap the previous piece about 2". Don't
install it completely up to the roof ridge because you'll need a opening for the
heat to escape. Leave the rafters open at least 6" from the roof top.

The gable ends should also have radiant barrier
installed. Staple the barrier to the studs, but make sure to leave room at the
top for the hot air to escape through the roof vents.

Okay, now you have the radiant barrier installed
in the attic. You have another problem if your attic was insulated with loose
fill insulation. You've walked on it and smashed it down in areas. Use a rake
and try to fluff it back into it's untouched condition. If you're unable you
should consider blowing new insulation over it as it has lost some of its
r-value.